1. Field of the Invention:
The theft resistant combination lug nut apparatus of the present invention relates to a nut for locking a tire rim to a wheel and which requires a special key device for removal thereof.
2. Description of the Prior Art:
As disclosed in my parent application, with the polularity of relatively expensive custom-made tire rims, many efforts have been made to provide a convenient means for locking such rims to the wheel but which provide for convenient and rapid removal thereof in the advent of a flat tire on such rim, thus necessitating replacement thereof by a spare tire. Since flat tires are frequently experienced in darkness and in inclement conditions, it is important that any key device to be used on a combination lug nut be easily fitted thereon with a minimum of inconvenience and tend to remain engaged with the nut during tightening thereof to avoid disengagement and consequent cracking of the operator's knuckles. Many efforts have been made to solve this problem and one such effort led to the proposal of a cylindrical nut having axially extending and radially outwardly opening grooves along one side thereof and registerable with a key device having complementarily positioned axially extending ribs formed on the interior thereof. A device of this type is shown in U.S. Pat. No. 1,447,564 and a somewhat similar groove and rib construction was shown in my parent application. However, I have learned that devices of this type suffer the shortcoming that there must be a close fit between the nut and key device, thus requiring critical axial and rotative alignment between the nut and key device in order to start the key device onto the nut and to prevent galling between the ribs and grooves during telescoping of such key device onto the nut. While a shroud may be installed over a lug nut of this type to assist in axially aligning the key device with the nut, such an arrangement would be practically unfeasible because of the inconvenience of installing such shroud and the likelihood of such shroud being deformed during use, thus preventing insertion of the key device. Obviously, acorn nuts having bell-shaped bonnets thereon are not formed with bearing rings having facets arranged in a selected pattern thereon so would present little difficulty in removal by a would-be thief.